GPU Calc: optimize GAMMINV

Change-Id: I103f8c70ad9b2517225fe2eee6d81f8e43e54614
Signed-off-by: I-Jui (Ray) Sung <ray@multicorewareinc.com>

sc/source/core/opencl/op_statistical.cxx

@@ -6349,9 +6349,10 @@ void OpGammaInv::GenSlidingWindowFunction(std::stringstream &ss,
     "            {\n"
     "                if (fPy!=fQy && fQy!=fRy && fRy!=fPy)\n"
     "                {\n"
-    "                    fSx = fPx * fRy * fQy / (fRy-fPy) / (fQy-fPy)"
-    "+ fRx * fQy * fPy / (fQy-fRy) / (fPy-fRy)"
-    "+ fQx * fPy * fRy / (fPy-fQy) / (fRy-fQy);\n"
+    "                    fSx = fPx * fRy * fQy *pow( (fRy-fPy),-1) *pow"
+    "( (fQy-fPy),-1)"
+    "+ fRx * fQy * fPy *pow( (fQy-fRy),-1) *pow( (fPy-fRy),-1)"
+    "+ fQx * fPy * fRy *pow( (fPy-fQy),-1) *pow( (fRy-fQy),-1);\n"
     "                    bHasToInterpolate = (fAx < fSx) && (fSx < fBx);\n"
     "                }\n"
     "                else\n"
@@ -6468,7 +6469,8 @@ void OpFInv::GenSlidingWindowFunction(std::stringstream &ss,
             ss << "))\n";
             ss << "            arg"<<i<<"= 0;\n";
             ss << "        else\n";
-            ss << "            arg"<<i<<"="<<vSubArguments[i]->GenSlidingWindowDeclRef();
+            ss << "            arg"<<i<<"="<<vSubArguments[i]->
+                                              GenSlidingWindowDeclRef();
             ss << ";\n";
             ss << "    }\n";
             ss << "    else\n";
@@ -6483,7 +6485,8 @@ void OpFInv::GenSlidingWindowFunction(std::stringstream &ss,
             ss << "))\n";
             ss << "        arg"<<i<<"= 0;\n";
             ss << "    else\n";
-            ss << "        arg"<<i<<"="<<vSubArguments[i]->GenSlidingWindowDeclRef();
+            ss << "        arg"<<i<<"="<<vSubArguments[i]->
+                                             GenSlidingWindowDeclRef();
             ss << ";\n";
 #endif
         }

sc/source/core/opencl/opinlinefun_statistical.cxx

@@ -238,7 +238,7 @@ std::string GetGammaInvValue =
 "        return 0.0;\n"
 "    else\n"
 "    {\n"
-"        double fX=fX1/fBeta;\n"
+"        double fX=fX1*pow(fBeta,-1.0);\n"
 "        double fLnFactor = fAlpha * log(fX) - fX - lgamma(fAlpha);\n"
 "        double fFactor = exp(fLnFactor);\n"
 "        if (fX>fAlpha+1.0)\n"